Table 1

Rates of cerebral palsy by birth weight and five year cohort for all cases and those with lifestyle assessment score (LAS) ⩾ 30%

		All weights			<1500 g^1-150				1500–2499 g				⩾ 2500 g
		Cases	Neonatal survivors		Rate	Rate LAS ⩾ 30%			Cases	Neonatal survivors			Rate	Rate LAS ⩾ 30%	Cases	Neonatal survivors	Rate	Rate LAS ⩾ 30%	Cases	Neonatal survivors	Rate	Rate LAS ⩾ 30%
1964–68	109^1-151	64866	1.68	0.98	12	201	59.7	29.8		23	3511	6.55	3.88		73	61154	1.19	0.74
1969–73	76	54635	1.39	0.76	6	262	22.9	9.15		21	3279	6.40	1.71		49	51094	0.96	0.64
1974–78	77	45122	1.71	0.80	4	145	27.6	9.18		22	2473	8.90	4.29		51	42504	1.20	0.56
1979–83	96	48079	2.00	1.47	18	222	76.6	75.7		21	2675	8.22	6.27		57	45182	1.26	0.83
1984–88	109	48095	2.27	1.72	23	303	75.9	47.0		27	2797	9.65	7.72		59	44995	1.31	1.06
1989–93	117	47691	2.45	1.96	28	350	80.0	74.2		33	2795	11.8	11.5		56	44546	1.26	0.83
χ² d.f. 5		p<0.001	p<0.001			p<0.05	p<0.01				NS	p<0.01				NS	NS
χ² for trend d.f. 1		p<0.001	p<0.001			p<0.01	p<0.01				p<0.05	p<0.001				NS	NS

↵1-150 No allowance has been made for birth weight groupings being lowered by 1 g in 1981 in line with WHO recommendations.
↵1-151 Includes one case with missing birth weight.
NS, not significant.